Forces and moments delivered by PET-G aligners to an upper central incisor for labial and palatal translation

Elkholy, Fayez; Panchaphongsaphak, Thanapon; Kılıç, Fatih; Schmidt, Falko; Lapatki, Bernd G.

doi:10.1007/s00056-015-0307-3

Cited by 47 publications

(57 citation statements)

References 20 publications

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“…We estimate that this value approximately corresponds to the suggested relative tooth displacement within single setup steps of 0.5 mm, because in the clinical situation, the elasticity of the periodontal ligaments of both displaced and anchorage teeth leads to smaller relative tooth displacements than those in the setup model. 15 Our results indicate that, even with the thinnest commercially available 0.5-mm aligner, median forces of À7.89 N for the labial and 8.37 N for the palatal displacement would be applied to a maxillary central, resulting in significant overloading of its periodontal structures. In view of this, it seems a remarkable finding of the current study that these forces can be significantly reduced by 35% and 71% when using the novel PET-G foils with a thickness of 0.4 and 0.3 mm, respectively.…”

Section: Discussionmentioning

confidence: 78%

“…11,13,15 This difference might be explained by use of the opposite-jaw-simulating device in the current study that prevented dislodgment of the aligner from the model. 15 A further interesting finding was the minimal average stiffness difference between the 0.5-mm and 0.625-mm (5%) as well as between the 0.625-mm and 0.75-mm (8%) aligner, which means that the 0.625-mm aligner could be omitted from the current aligner prescription without diminishing the efficiency of treatment. Additionally, because of the form instability of the 0.3-mm aligner, it can be concluded that PET-G aligners of this thickness are not suitable for clinical use.…”

Section: Discussionmentioning

confidence: 85%

“…15 In this study, we explored the second approach by investigating the biomechanical behavior of novel aligners with a reduced thickness of 0.4 mm and 0.3 mm, respectively, and comparing the results with the commercially available thinnest aligners having a thickness of 0.5 mm. During our experiment, the selected maxillary right central incisor was bodily displaced by 60.25 mm.…”

Section: Discussionmentioning

confidence: 99%

“…Results clearly indicated that the teeth are overloaded when following the recommendations regarding tooth displacements in the setup and aligner materials. 11,[13][14][15] For instance, force values of up to eight times those recommended for tipping a maxillary central incisor were recorded for the thinnest commercially available aligner material with a thickness of only 0.5 mm. 15 It might be speculated that such overloading of single teeth by aligners might increase the risk of root resorption.…”

Section: Introductionmentioning

confidence: 99%

“…11,[13][14][15] For instance, force values of up to eight times those recommended for tipping a maxillary central incisor were recorded for the thinnest commercially available aligner material with a thickness of only 0.5 mm. 15 It might be speculated that such overloading of single teeth by aligners might increase the risk of root resorption. However, there is only one in vivo study published concluding that the risk of root resorption is similar for treatment with aligners and fixed appliances.…”

Section: Introductionmentioning

confidence: 99%

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Forces and moments delivered by novel, thinner PET-G aligners during labiopalatal bodily movement of a maxillary central incisor: An in vitro study

Elkholy

Schmidt

Jäger

et al. 2016

The Angle Orthodontist

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Objective: To evaluate whether overloading of teeth can be avoided by utilizing aligners with reduced thicknesses of 0.4 mm or 0.3 mm. Materials and Methods: The experimental setup included an acrylic maxillary jaw model with tooth 11 separated and fixed via a 3-D force-moment transducer to a hexapod for experimental movement. Aligners tested were fabricated on duplicate stone models using commercially available polyethylene terephthalate glycol (PET-G) foils with thicknesses between 0.5 and 0.75 mm, and novel 0.4-mm-and 0.3-mm-thick foils. With the test aligner seated, 11 was bodily displaced in a labiopalatal direction in the range of 60.25 mm while all six force-and-moment components exerted on this tooth were registered. Results: With the thinnest commercially available 0.5-mm aligner, median forces of À7.89 N and 8.37 N were measured for the maximum 0.25-mm movement of 11 in a labial and palatal direction, respectively. In comparison, force values were 35% and 71% lower for the novel aligners with a thickness of 0.4 mm and 0.3 mm, respectively. Conclusions: Novel ''leveling'' aligners with reduced thickness may reduce overloading of individual teeth during aligner therapy. Due to form instability of 0.3-mm aligners, we suggest a novel sequence of 0.4-0.5-0.75 mm for aligner systems using several foil thicknesses for load graduation within single setup steps. This would combine low stiffness of the initial aligner and relatively constant load increases throughout the treatment. (Angle Orthod. 2016;86:883-890)

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Forces and moments delivered by novel, thinner PET-G aligners during labiopalatal bodily movement of a maxillary central incisor: An in vitro study

Elkholy

Schmidt

Jäger

et al. 2016

The Angle Orthodontist

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Computational design and engineering of polymeric orthodontic aligners

Barone

Paoli

Razionale

et al. 2016

Numer Methods Biomed Eng

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Transparent and removable aligners represent an effective solution to correct various orthodontic malocclusions through minimally invasive procedures. An aligner-based treatment requires patients to sequentially wear dentition-mating shells obtained by thermoforming polymeric disks on reference dental models. An aligner is shaped introducing a geometrical mismatch with respect to the actual tooth positions to induce a loading system, which moves the target teeth toward the correct positions. The common practice is based on selecting the aligner features (material, thickness, and auxiliary elements) by only considering clinician's subjective assessments. In this article, a computational design and engineering methodology has been developed to reconstruct anatomical tissues, to model parametric aligner shapes, to simulate orthodontic movements, and to enhance the aligner design. The proposed approach integrates computer-aided technologies, from tomographic imaging to optical scanning, from parametric modeling to finite element analyses, within a 3-dimensional digital framework. The anatomical modeling provides anatomies, including teeth (roots and crowns), jaw bones, and periodontal ligaments, which are the references for the down streaming parametric aligner shaping. The biomechanical interactions between anatomical models and aligner geometries are virtually reproduced using a finite element analysis software. The methodology allows numerical simulations of patient-specific conditions and the comparative analyses of different aligner configurations. In this article, the digital framework has been used to study the influence of various auxiliary elements on the loading system delivered to a maxillary and a mandibular central incisor during an orthodontic tipping movement. Numerical simulations have shown a high dependency of the orthodontic tooth movement on the auxiliary element configuration, which should then be accurately selected to maximize the aligner's effectiveness.

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Investigating the role of aligner material and tooth position on orthodontic aligner biomechanics

Kaur¹,

Khurelbaatar²,

Mah

et al. 2022

J Biomed Mater Res

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The primary objective of this work was to investigate the effect of material selection and tooth position on orthodontic aligner biomechanics. Additionally, material property changes with thermoforming were studied to elucidate its role in material performance in-vitro. An orthodontic simulator (OSIM) was used to evaluate forces and moments at 0.20 mm of lingual displacement for central incisor, canine and second premolar using Polyethylene terephthalate (PET), Polyurethane (PU) and Glycol-modified polyethylene terephthalate (PET-G) materials. The OSIM was scanned to generate a model used to fabricate aligners using manufacturerspecified thermoforming procedures. Repeated measures of MANOVA was used to analyze the effect of teeth and material on forces/moments. The role of thermoforming was evaluated by flexural modulus estimated by 3-point bend tests. -Pre-thermoformed and post-thermoformed samples were prepared using as-received sheets and those thermoformed over a simplified arch using rectangular geometry, respectively. Groups were compared using Two-way ANOVA. The PET, PU, and PET-G materials exerted maximum buccal force and corresponding moments on the canine. PU exerted more buccal force than PET-G on the canine and second premolar, and more than PET on the second premolar. The impact of thermoforming varied according to the specific polymer: PET-G remained stable, there was a slight change for PET, and a significant increase was noted for PU from pre-thermoformed to post-thermoforming. The results of this study elucidate the influence of material and arch position on the exerted forces and moments. Further, the mechanical properties of thermoplastic materials should be evaluated after thermoforming to characterize their properties for clinical application.

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Forces and moments delivered by PET-G aligners to an upper central incisor for labial and palatal translation

Cited by 47 publications

References 20 publications

Forces and moments delivered by novel, thinner PET-G aligners during labiopalatal bodily movement of a maxillary central incisor: An in vitro study

Forces and moments delivered by novel, thinner PET-G aligners during labiopalatal bodily movement of a maxillary central incisor: An in vitro study

Computational design and engineering of polymeric orthodontic aligners

Investigating the role of aligner material and tooth position on orthodontic aligner biomechanics

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